The invention is directed to a light having a non-uniform light emission, i.e. a light wherein the light emission characteristics are different in various regions.
Lights with different light emission characteristics were hitherto realized in that the light technology of two different lights was integrated into one housing, i.e., ultimately, two lamps having a respectively separate bulb, a separate reflector and the like, were integrated in one housing. It has also been proposed to split the light of a bulb into a direct and into an indirect light part with suitable design of the reflectors. In addition, for example, EP-0 638 764 B1 discloses that a part of the light of a bulb that outputs light via a first light exit face is conducted to a second light exit face.
These latter proposals have in fact proven themselves in practice. It is nonetheless disadvantageous that the splitting of the light of the bulb and conducting it to the respective, different light exit faces was complicated with the traditional technologies. This was particularly true when a shielding of the emerging light was to be respectively produced at the various light exit faces.
The invention is based on the object of making a new lighting fixture type available wherein different emission properties in different regions can be realized more simply then previously.
Inventively, this object is achieved by a lighting fixture that has a plurality of differently fashioned regions which have different light emission properties. The lighting fixture has at least one hollow light guide having a cavity, one or more bulbs that emit light into the cavity of the hollow light guide, and at least one light output device having a light-refractive structure for outputting light from the cavity of the hollow light guide to a light exit face, the light output device or, respectively, the light output devices form walls of the hollow light guide or a part thereof, and the light of at least one bulb that beams light into the hollow light guide is beamed out in different regions of the lighting fixture that have different light emission properties.
The invention can provide that the hollow light guide comprises a plurality of differently fashioned regions which have different light output properties.
The invention can provide that the hollow light guide comprises a plurality of differently fashioned regions so that the light output via a light output device has different properties.
It can be provided that the light emitted via a light exit face of the lighting fixture in a first region has a symmetrical light intensity distribution curve and has an asymmetrical light intensity distribution curve in a second region.
It can be provided that a light output device has a plurality of regions having different light-refractive structures, particularly structures having a different light refraction behavior, for example prism structures with the same refractive index having a different prism angle for the light output.
In particular, a structure can be provided in a first region that generates a shielded light intensity distribution curve and a structure can be provided in a second region that generates a wide-angle, essentially non-shielded light intensity distribution curve that can be asymmetrical or exhibit a minimum at small angles.
It can also be provided that the light output device comprises two agents offset in the direction of a lamp axis that has a different light-refractive structure.
It can also be provided that a first region having a first light-refractive structure surrounds a second region having a second light-refractive structure on a plurality of sides. For example, the first region can adjoin the second region at two or three sides or can also completely surround it.
The invention can provide that a structure having prisms or prism-like elements with a prism angle of more then 90xc2x0, particularly 90xc2x0 through 130xc2x0, and preferably 110xc2x0 through 128xc2x0 is provided in a first region, and a structure having prisms or prism-like elements with a prism angle of 55xc2x0 through 80xc2x0, preferably 60xc2x0 through 75xc2x0, is provided in a second region, respectively having a refractive index of 1.49 or, for a different refractive index having prism angles that lead to the same refraction behavior.
The invention can also provide that a reflective wall residing opposite a light output device, particularly a cap reflector, is differently fashioned in different regions offset along the direction of a lamp axis.
It can be provided that a reflective wall residing opposite a light output device comprises two regions offset in the direction of the lamp axis. The wall is differently curved with reference to a plane residing perpendicularly relatively to the lamp axis or is inclined relative to the light output device.
It can also be provided that a reflective wall residing opposite a light output device is directed relative to a lamp in a first region so that the light incident onto the wall from the lamp is incident essentially at a side facing toward the cavity and is reflected into the cavity. In a second region, the light of the same lamp, which is incident onto the wall, is reflected at least partially and may be completely reflected onto that side facing away from the cavity and is therefore reflected away from the cavity for output of an indirect light part.
In particular, the invention can provide that a lamp inputs light into the cavity, at least in regions, via a side between a reflective wall residing opposite a light output device and the light output device. The distance of the reflective wall from the surface wherein the light output device lies is greater in a first region of the hollow light guide than in a second region offset from the first region in the direction of the axis of the lamp. The distance can disappear in a second region or returned to zero, so that the light of the lamp is emitted entirely or partially past the hollow waveguide and can be employed as indirect light part of the lighting fixture.
The invention can provide that a lamp beams light onto the reflective wall only in a part of the offset regions, particularly in only one such region.
The invention can provide that a light output face comprises a first region having a first average luminous intensity and a second region adjoining the first region and having a second average luminous intensity that is lower than the first luminous intensity. In this way, a soft transition of the luminous intensity to the surroundings can be produced.
The invention can provide that the light output device comprises a planar, light-transmissive element, particularly a foil or plate, and a part of this element is provided with a partially light-transmissive coating that is preferably fashioned partially reflective in the direction of the cavity.
The invention can provide that an element that reduces the light intensity, for example a foil or plate, precedes or follows an element having a light-refractive structure in a sub-region in the light output device. This additional element need not necessarily comprise a light-refractive structure and preferably precedes said light-refractive structure.
The invention can provide that a partially light-transmissive element is arranged in the inside of the cavity at a distance from the light output device, and the element reduces the light intensity of the light incident onto a sub-region of the light output device. This element can, in particular, be a partially light-transmissive and a partially reflective plate or foil that is arranged spaced from the light output device between the light output device and a wall that lie opposite the light output device and that extends over a sub-region of the cavity.
It can also be provided that an element is arranged in the inside of the cavity of the hollow light guide spaced from the light output device. This element is arranged between the light output device and a wall lying opposite the light output device and extending over a sub-region of the cavity and is fashioned reflective at that side facing toward the light output device and at that side lying opposite this side. The sub-region of the cavity between this element and the light output device thereby has at least one open side via which light can pass from the remaining cavity into this sub-region. The geometrical limitation of the light incidence produced by the element leads to a reduction of the luminous intensity in a sub-region of the light exit surface. As a result of this reflective formation at two sides, the light beamed into the cavity from the lamps can be largely completely utilized.
It can also be provided that the light intensity distribution curve in the region having reduced luminous intensity covers a larger angular range than in the region having higher luminous intensity.
It can also be inventively provided that the light output device is followed by a device that reduces the luminous intensity on a part of the light exit face, for example a partially absorbent foil or the like.
It can also be provided that a light exit face comprises a first region and a second region adjoining the first region wherein the emerging light has a different color than in the first region.
It can also be provided that a coloring device for producing a specific color of the light emerging from the light output device is provided in a sub-region of the light output device in the cavity and/or at the light output device.
It can also be provided that the light output device comprises a planar, light-transmissive element, particularly a foil or plate, that is entirely or partially coloring, for example due to a coloring coating or structuring, so that the coloring region of this element forms a sub-region of the light output device.
It can also be provided that a coloring element that modifies the color of the light incident onto a sub-region of the light output device is arranged in the cavity at a distance from the light output device. This element can, in particular, be a color-selective plate or foil that is arranged between the light output device and a wall lying opposite the light output device spaced from the light output device and that extends over a sub-region of the cavity.
It can also be provided that an element reflective on both sides is arranged in the inside of the cavity spaced from the light output device. The element is arranged between the light output device and a wall lying opposite the light output device and extends over a sub-region of the cavity. A side of this element facing toward the light output device is fashioned in a coloring fashion, which side, for example, is correspondingly coated or structured.
It can also be provided that the light output device or an element of the light output device is followed by a color-selective device that modifies the color of the emerging light on a part of the light exit face.
It can also be provided that the luminous intensity in the region of the light exit face is lower in a region wherein chromatic light is emitted than in a region wherein white light is emitted.
It can also be provided that the light output device comprises a sub-region without a light-refractive structure such as a prism structure as described above that deflects the passing light in a directed fashion.
It can also be provided that the light output device comprises a no light-refractive structure that deflects the passing light in a directed fashion in a sub-region and an element that limits the luminous intensity and/or creates a color light is arranged to be effective in the sub-region.
The invention can also provide that the lighting fixture comprises a plurality of regions offset in the direction of the axis of a lamp having different emission properties, and the lamp contributes to the light emission in only some of these regions.
In particular, it can be provided that the lamp extends only over a part of these regions.
The invention can provided that the light output device comprises at least one light-transmissive element having a boundary surface between two media with a different refractive index and the element is provided with a light-refractive structure that essentially prevents a light emission above a limit angle in at least one plane perpendicular to the light exit face so that a shielding of the light emerging at the light exit face is produced in this plane.
What is understood by a shielding is the lowering of the average luminous intensity of the light exit face above a limit angle relative to a perpendicular vis-a-vis the light exit surface below a predetermined limit value.
The invention can provide that the light-refractive structure or, respectively, the light-refractive structures of the light output device that, in particular, can be fashioned in plates or foils, comprises or is composed of line-shaped, light-refractive structural elements. These elements comprise sidewalls essentially parallel to the line direction that describe an angle at the free ends of the structural elements that is greater than 90xc2x0 according to one embodiment and that preferably lies in a range from 90xc2x0 through 130xc2x0 for lighting fixtures having a shielding. According to a particular embodiment of the invention, the angle can lie in a range from 110xc2x0 through 128xc2x0. The angular ranges of 90xc2x0 through 130xc2x0 or, respectively, 110xc2x0 through 128xc2x0 recited above are preferred especially for plates composed of a material having a refractive index of approximately 1.49, but the range can also be employed given materials having a different refractive index that is not all that different from 1.49. This applies to standard materials such as polymethylmethacrylate or glass. Fundamentally, however, the preferred angular ranges can be different for materials having a refractive index different from 1.49, and these preferred angular ranges for these refractive indices can be determined so that the same shielding angles are achieved for a predetermined limit value of the luminous intensity as in the above-recited angular range from 90xc2x0 through 130xc2x0 or, respectively, 110xc2x0 through 128xc2x0 given a refractive index of 1.49. According to the preferred embodiments, however, this angle should fundamentally be greater than 90xc2x0 independently of the refractive index given lighting fixtures having a shielding. Preferably, this angle is the same at all structural elements that, moreover, can also have the same cross-sectional shape and, potentially, identical dimensions as well. For non-shielded light intensity distributions, the relevant angular ranges can be different, whereby the prism angle preferably differs from 90xc2x0.
The limit value of the luminous intensity can lie at 200 cd/m2, 500 cd/m2 or 1000 cd/m2 for shielded lighting fixtures given the prevailing standards or, respectively, proposed standards. The shielding angle in standard applications lies in the range of more than 45xc2x0, preferably in a range from 50xc2x0 through 75xc2x0, and more preferably in a range from 50xc2x0 through 65xc2x0.
According to the preferred exemplary embodiment of the invention, the light-refractive elements have a constant cross-section along the line direction that, in particular, can assume the shape of a triangle. The sidewalls of the elements, however, need not be planar but can also be curved. Whereas the sidewalls according to a preferred embodiment directly adjoin one another at the free end of the structural elements, it can also be provided that the free end of the structural elements is flattened, and the sidewalls are connected by a planar or curved surface. In the case of planar lateral surfaces or lateral surfaces having a planar section at the free end, the aforementioned angle is then determined by the imaginary extension of the planar sidewalls or, respectively, of the planar sections of the sidewalls. In the case of curved sidewalls, the aforementioned angle can correspond to the angle of a triangle that the cross-section of the light-refractive elements optimally describes, i.e. with optimally little area deviation between the area of the triangle and the cross-sectional area of the light-refractive element. In the case of a convex, i.e. outwardly curved sidewall, this angle would be formed by the intersection angle of two tangents that are applied to the sidelines of the cross-section of the light-refracted element, whereas, given a concave, i.e. inwardly curved sidewall, this angle would be defined by two straight lines that are respectively placed between the head point and the foot point with a sideline of the cross-section, i.e. a line corresponding to the sidewall in cross-section.
It can be inventively provided that a light-refractive structure with line-shaped structural elements is respectively fashioned in two plates or foils arranged above one another. The lines that define the geometry of the structure of the first plate describe a non-disappearing angle with the lines that define the geometry of the structure of the second plate and preferably reside perpendicularly thereon.
Instead of the aforementioned, line-shaped structures, other light-refractive structures can also be employed, for example structures shaped like a truncated pyramid as disclosed, for example, by U.S. Pat. Nos. 5,396,350 and 5,555,109. The light-refractive structure also need not necessarily produce a shielding but, for example, can influence the position of the maximum of the light intensity distribution curve given a wide-angle lighting fixture.
The light-refractive structures can, for example, be manufactured in that a plate or foil of a standard light-transmissive material such as glass, polyester, polystyrol, polycarbonate, PET or polymethylmethacrylate is correspondingly processed or shaped on a surface. Alternatively, a foil that contains the light-refractive structure can be glued onto such a plate.
Further features and advantages of the invention are derived from the following detailed description of the exemplary embodiments, the drawings and claims.